The present application claims priority to Japanese Application Nos. P2000-166401 filed Jun. 2, 2000, and P2000-238188 filed Aug. 7, 2000 which application are incorporated herein by reference to the extent permitted by law.
The present invention relates to a system for checking a wiring configuration of a printed circuit board, and in particular, it relates to a system for checking a wiring configuration on a printed circuit board provided with a function to check an electromagnetic influence of a high speed signal line laid on a power supply plane to other signal line layers.
A conventional printed circuit board used in recent electronic device has lines for high speed signals (hereinafter, referred to as a high speed signal wiring) laid out on a power supply plane. If this high speed signal wiring is laid out in the vicinity of an edge of a ground-plane layer which functions as a reference as is normally done or in the vicinity of an edge of the power supply plane layer, there occurs such a problem that an electromagnetic field generated from the above-mentioned high speed signal wiring passes over the ground-plane layer functioning as a reference or the power supply plane layer, and reaches to other signal line layer or another ground (power supply) plane layer, thereby causing an electromagnetic coupling to occur.
The above-mentioned electromagnetic field generated from the high-speed signal wiring has sometimes caused a malfunction or spurious radiation noise depending on conditions of the use.
Further, the above-mentioned phenomenon may induce not only the electromagnetic coupling to the other wiring but also cause resonance phenomena with ground-plane layers or power supply plane layers.
However, in conventional low speed digital signal lines, because of a relatively moderate electromagnetic energy of the low speed digital signal, influences to other signal lines and/or spurious radiation thereof did not appear so significantly. Further, if its wiring density were not so great, any high speed signal wiring which is likely to cause the problem may easily be rearranged to be laid out far from the edge of the plane layer toward a center of the board, thereby preventing an occurrence of any adverse effect on other signal lines.
With a recent trend for a faster speed, a number of high speed signal lines is increasing, and also with an increasing demand for a light-weight, thinner, shorter and compacter design as well as a provision of multi-function, a wiring density within a printed circuit board is increasing more and more, thereby inevitably introducing such a condition (a condition to be described later in which xe2x80x9cdistxe2x80x9d in FIG. 1 must be shortened) that the high speed signal lines cannot be helped but to be laid out near to the edge portion of the board (nearer to the edges of the ground-plane layer or power supply plane layer). As a result, actually there are such cases in which their high speed signal lines must have been laid out toward the edges of the ground-plane layer (same as the board edge) or the power supply plane layer, thereby substantially increasing a radiation noise from the edge portion of the board.
Further, there has been such a problem associated with the conventional art that an appropriate position of lay-out of a certain high speed signal line causing a problem cannot be determined precisely how far from the edge portion and how near to the center of the board it should be laid out to solve the problem.
The present invention has been contemplated to solve the above-mentioned problem associated with the conventional design of the printed circuit board. An object of the present invention is to provide a system for checking wiring configuration of a printed circuit board. Another object of the present invention is to provide a system capable of specifying an appropriate position of wiring lay-out for high speed signals on a power supply plane. Here, the appropriate position of lay-out is such a position capable of alleviating adverse electromagnetic effect on other wiring layers.
In order to solve the above-mentioned problems, a wiring configuration check system for checking a configuration of a wiring which is tentatively designed and laid out on a printed circuit board is provided in accordance with one embodiment of the present invention. The system in accordance with the one embodiment of the present invention may comprise: an object determination unit for determining presence of a high speed signal wiring by extracting (sampling) a combination of a driver and a receiver one by one from a group of components existing on the above-mentioned wiring, extracting circuit information relating to a driver corresponding to one of the combination, and on the basis of a result of evaluation using a determination expression which contains at least a part of the circuit information as its variable; a segment extract (sample) unit for extracting a segment which is nearest to an edge of the board from a group of segments each defining a set of a minimum unit of configuration of the above-mentioned wiring; a plane edge specifying unit for specifying a plane edge which has a shortest perpendicular distance relative to the wiring connecting between a driver and a receiver in the segment by investigating its wiring configuration of the segment extracted above; a perpendicular distance measuring unit for measuring a perpendicular distance relative to the wiring extending from the driver to the receiver in the segment; an interlayer distance computing unit for computing a minimum interlayer distance required between the wiring layer of the segment and the plane layer, on the basis of a type of the wiring configuration and a circuit design specification of the segment extracted above; a distance determination unit for comparing the perpendicular distance measured above and the interlayer distance computed above; and a message display unit for displaying a message containing a predetermined instruction corresponding to the wiring based on a result of determination by the distance determination unit.
In accordance with another embodiment of the present invention, a wiring design support system is provided for supporting a design of a signal line wiring on a circuit board. The design support system of the another embodiment of the present invention may comprise: a confirmation unit for confirming a presence of a high speed signal line on a power supply plane; a unit for measuring a lay-out of a high speed signal line wiring if there exists the high speed signal line wiring, and which was tentatively designed on the power supply plane (namely, a perpendicular distance xe2x80x9cdistxe2x80x9d from the edge of the ground-plane layer or the power supply plane layer to the wiring), computing a minimum distance required (for the above-mentioned perpendicular distance of the lay-out of the high speed signal line wiring) using predetermined mathematical expressions, on the basis of the circuit design specification of the high speed signal line wiring, and comparing the perpendicular distance xe2x80x9cdistxe2x80x9d measured above with the minimum distance required therefor computed above; and a unit for displaying an appropriate message corresponding to a specified name of the signal wiring if the perpendicular distance xe2x80x9cdistxe2x80x9d measured above does not exceed the minimum distance required therefor computed above, thereby enabling a very efficient wiring design support task to be executed.